BASTION Laser Engraved Rear Cover Slide Back Plate for Glock - See Description for Model List. Gen 1-4 only, not Gen 5. Does not fit Glock 42 or 43 Models. Zero FCKS High resolution, durable lasered artwork wont rub off or wear off, not painted. Asterisk replaces letter U in F word. Black hard coat, hardcoat, anodized finish. Premium billet, mil-spec, aircraft grade, T6, machined aluminum, not plastic. Easily installed, replaces plastic factory part. Fits Gen 1-4 only, not compatible with Gen 5. Not compatible with G42 or G43. Fits Glocks Model G17 G19 G21 G22 G23 G24 G26 G27 G29 G30 G31 G32 G33 G34 G35 G36 G37 G38 G39 G40 G41 Quick easy install, Factory replacement, no permanent modifications needed to install. Dozens of other designs available, custom engraving too!